Comments at Arlington County Board Meeting, February 20, 2020.
Last month Arlington County Board member Libby Garvey objected to my claim that the County had ignored the recommendation of Dr. John Field on how to remedy erosion along Tributary B of Donaldson Run. She characterized my remarks as both inaccurate and unfair. Yet the 2021 Capital Improvement Plan (CIP) has a line item of $2.5 million to shore up the Donaldson Run watershed by flattening the streambed of Tributary B (p. 15).
In this process, known euphemistically as Natural Channel Design (NCD), 80 trees on either side of the stream will be clear cut. According to Dr. Field, who is a nationally recognized river scientist, NCD will actually induce more erosion by increasing the slope of the stream bed as it drops along the Piedmont fall line to the Potomac River.
Libby observed that experts disagree. The County, having done due diligence on the project, decided some time ago to go ahead with the advice of NCD experts.
Yet expert opinion seems to be going the other way. According to a recent eblast from Rod Simmons, a natural resource manager and plant ecologist within Alexandria’s Department of Recreation, Parks and Cultural Activities, a report by the Chesapeake Stormwater Network
“suggests that natural channel design (NCD) is being phased out, . . . as well as upper headwater streams as project target locations to some extent, with projects now moving downstream to streams with true floodplains that are wide enough to capture and naturally process nitrogen.”Rod Simmons
If that’s the case then Arlington County should reconsider whether Natural Channel Design—an oxymoron if there ever was one–is appropriate for an upper headwater stream like Donaldson Run.